Study On Failure Mechanism And Support Timing Of Soft Rock Roadway With Overlying Aquifer

The coal seam mined in Qing Shui-ying Coal Mine is located under the weak soft rock aquifer, with rich water contentency, the surrounding rocks can easily break, with large quantity of construction rework and maintenance difficulty. In this paper, with field investigation, field monitoring, theoretical analysis and numerical simulation, the above problems are studied. The main findings are as follows:(1) According to the deformation shape and characteristics of the soft rock roadway and the influence factors of the soft rock roadway deformation are obtained, the roof and floor deformation mechanism of the soft rock roadway is discovered.(2) It is obtained the judgment basis of suitable support timing for soft rock roadway:First bolt-net support should be conducted when the roof settlement is 24mm, and second strength bolt-anchor support should be conducted when the roof settlement is 43mm.(3) The analyzing results of FLAC3D numerical simulation software show that, the surrounding rock conditions of roadway are changed and the self-supporting capability is increased after bolt-net-anchor coupling support.The above study results have some reference value on the ground pressure control of soft rock roadway with overlying aquifer in this mine.